LTE-A (long term evolution-advanced) is a further evolved and enhanced system of an LTE system. In the LTE-A system, to satisfy the peak data rate requirement of International Telecommunication Union for the 4th generation communication technology, a carrier aggregation (CA) technology is introduced, which is also referred to as a spectrum aggregation technology or a bandwidth extension technology. In the carrier aggregation, spectrums of two or more component carriers are aggregated to obtain a larger transmission bandwidth. The spectrum of each component carrier may be adjacent continuous spectrums or non-adjacent spectrums in the same frequency band or even discontinuous spectrums in different frequency bands. A user equipment (UE) of LTE Rel-8/9 can only access one of the component carriers to perform data transmitting and receiving, while a user equipment of the LTE-A may access multiple component carriers at the same time to perform data transmitting and receiving according to capability and a service requirement of the user equipment.
In order to support technologies such as dynamic scheduling and downlink multiple input multiple output (MIMO) transmission and hybrid automatic retransmission, a terminal needs to feed back uplink control information (UCI) to a base station, which includes channel state information CSI and hybrid automatic repeat request-acknowledgment information (HARQ-ACK), where the hybrid automatic repeat request-acknowledgment information may also be simply referred to as ACK (Acknowledgment, acknowledgment information)/NACK (Negative Acknowledgment, negative acknowledgment information). In the LTE-A, since the carrier aggregation technology is introduced, when a user equipment accesses multiple downlink component carriers at the same time to receive downlink data, for each downlink component carrier, the user equipment needs to feed back its channel state information in an uplink direction, and for data scheduled on the each downlink component carrier, the user equipment also needs to feed back its hybrid automatic repeat request-acknowledgment information in the uplink direction. Therefore, the channel state information and the hybrid automatic repeat request-acknowledgment information may need to be reported on an uplink subframe at the same time, where the channel state information to be reported may correspond to one or multiple downlink carriers and the hybrid automatic repeat request-acknowledgment information to be reported may also correspond to one or multiple downlink carriers.
The CSI includes periodic CSI and non-periodic CSI. The periodic CSI includes information such as a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indication (RI) and a precoding type indicator (PTI). The periodic CSI has multiple reporting modes on a physical uplink control channel (PUCCH). For example, in an LTE Rel-10 system, reporting modes of the periodic CSI include mode 1-0, mode 1-1, mode 2-0 and mode 2-1. A reporting mode corresponds to multiple reporting types and different reporting types correspond to different reported content. For example, in the LTE Rel-10 system, the periodic CSI includes the following several reporting types: type 1 (Type 1), supporting sub-band CQI feedback selected by a user equipment; type 1a (Type 1a), supporting sub-band CQI and second PMI feedback; type 2a (Type 2a), supporting wideband PMI feedback; type 3 (Type 3), supporting RI feedback; type 4 (Type 4), supporting wideband CQI feedback; type 5 (Type 5), supporting RI and wideband PMI feedback; and type 6 (Type 6), supporting RI and PTI feedback. Different reporting types of the periodic CSI correspond to different reported content and different reported content corresponds to different performance goals and requirements, so different reporting types of the periodic CSI correspond to different performance goals and requirements. For example, the performance goal and requirement of the Type 3 is block error rate BLER=10e−3, while the performance goal and requirement of the type 4 is block error rate BLER=10e−2.
A base station semi-statically configures a reporting mode, a reporting period and a subframe offset of the periodic CSI of each carrier through high-layer signaling, a user equipment determines, according to the reporting mode indicated by the high-layer signaling, the reporting type corresponding to the CSI to be reported, and determines the reporting moment of the CSI of each reporting type according to the reporting period and the subframe offset indicated by the high-layer signaling. For each carrier, the CSI of only one reporting type is reported at a reporting moment. The reporting modes of the periodic CSI of different carriers may be the same or may be different. In a scenario of carrier aggregation, the channel state information of multiple downlink carriers may need to be reported on one subframe, so the CSI of different reporting types from different carriers may be reported on the one subframe.
Therefore, in a scenario of LTE-A carrier aggregation, the channel state information and the hybrid automatic repeat request-acknowledgment information may need to be reported on an uplink subframe at the same time. The channel state information to be reported may be corresponding one or multiple downlink carriers, and when the channel state information to be reported corresponds to multiple downlink carriers, the reporting type of the periodic CSI corresponding to each downlink carrier may be the same or different; and the hybrid automatic repeat request-acknowledgment information to be reported may also be corresponding one or multiple downlink carriers. However, because the performance goals and requirements corresponding to the CSI of different reporting types are inconsistent, and the performance goals and requirements corresponding to the periodic CQI/PMI are also inconsistent with the performance goals and requirements of the hybrid automatic repeat request-acknowledgment information, how to ensure that both the CSI of different reporting types and the hybrid automatic repeat request-acknowledgment information reach a performance requirement is a problem to be solved.
A solution is to jointly encode all uplink control information to be transmitted, and on a subframe with uplink control information of different performance goals and requirements for feedback, improve the transmission power, so that the UCI with a high performance goal and requirement can also reach the performance goal.
However, in the solution, to enable that the UCI of that type with high performance goal and requirement can also reach the performance goal, the user equipment adopts higher transmission power when sending the UCI, but for the UCI of that type with low performance goal and requirement, the transmission power is excessively high, thereby wasting the transmission power of the user equipment and lowering the power utilization efficiency.
The solution is inapplicable to a user equipment with limited power. If power of the user equipment is limited, the user equipment cannot increase the transmission power, and therefore, the UCI of that type with high performance goal and requirement cannot reach the performance requirement through the method for increasing the transmission power.